Tobacco cigarette vs e-cigarette nicotine equivalency

[rolygate]

Can we determine a tobacco vs e-cig nicotine equivalency? Is it possible to say, "One cigarette equals X number of puffs on an e-cigarette, or, X minutes of vaping" ?

Can we say how much nicotine in an e-cigarette cartridge is equal to - for the individual - the nicotine in one tobacco cigarette?

Can we say how much nicotine in tobacco smoke is equivalent to how much nicotine in e-cig vapor?

Broadly, the answer is no - there are too many variables. In the end, only the individual can decide this. Partly this is due to the fact that the e-cigarette is an extremely flexible clean nicotine delivery system, where any of multiple variations will affect the outcome; and partly because there is a wide variation in the individual tolerance to nicotine. The end result will be different for each individual.

We have seen a factor-10 variation in nicotine tolerance between individuals reporting the effects of nicotine, here on ECF. For example, some users report symptoms of nicotine OD immediately on use of 6mg strength liquid (0.6%), whereas some report no signs of nicotine OD whatsoever with unrestricted use of 36mg liquid (3.6%), with some reports of users employing 48mg (4.8%) and even 60mg (6%) ad lib. Therefore, any equivalency is moot, since the user varies the result to suit their own preference.

For interest value, here are some of the issues. These have confused government departments, so do not be alarmed if you feel some light-headedness coming on. Just lower your nic intake... We have all the references in the literature for the numbers quoted and statements made below. Not being chemists or researchers who work with tobacco, we must go to the literature.


Part 1: Tobacco cigarettes

Raw materials: Tobacco Cigarettes
A cigarette contains between 13mg and 23mg of nicotine.
This means the tobacco in a cigarette, as it comes out of the pack, before being ignited - in other words a test of the materials before conversion to a user-consumable form.
This is not the same as what the user is presented with. We need to test the smoke, for that.

Usable materials delivery - smoke
Cigarette (mainstream) smoke contains an average of 1mg per cigarette. This means that the smoke from the average cigarette, when measured by agreed procedures (i.e. standard protocols, which have to be agreed, documented and followed otherwise the results will be different for every test) will supply about 1mg of nicotine to the user's oral cavity.
This is not the same as what is actually usable by the consumer - for example, nicotine measured in this way, in the form of smoke, might not be able to be used or metabolysed by the user. We need to test their bloodstream for nicotine, to establish this.

User tests - smoke
A smoker's bloodstream typically shows from 10 to 50 ng/ml of nicotine. This is sufficient for the smoker to be satisfied.
This means they do get nic from cigarette smoke, and it's measurable, and it does the job.
Its metabolytes such as cotinine can also be measured in the urine, and there is a relationship between the amount of cotinine measured versus the amount of nicotine consumed and the time elapsed since consumption.
What this tells us is that smokers get nicotine from cigarettes, the effect is measurable in the bloodstream and elsewhere, and it does the job.
We have not measured the other WTAs*, and their effects are currently unknown to research (we believe).
We also know that cigarette smoke has an extremely small particulate size, that this means the smoke gets down into the finest air passages of the lungs, and that the nic hit from smoking can occur in as little as seven seconds, which is very fast.
* There are several active alkaloids in tobacco apart from nicotine


Part 2: Electronic cigarettes

Raw materials: Electronic cigarettes
A typical e-cigarette cartomizer (not a cartridge, which is smaller) contains about 1ml of liquid (item: Boge 1ml carto, 35mm length, 9mm dia.). Not all can be used as some is retained by the filler material. We might estimate that 80% of the liquid can be used.
An e-cig carto may contain liquid of a strength up to 36mg, which means 36mg/ml, or 3.6%. That is, 3.6% of the liquid is nicotine, and 1ml of liquid contains 36mg of nicotine.
This means the available nicotine in an e-cigarette, in a regular carto, before use - in other words a test of the materials before conversion to a user-consumable form, and for the strongest retail liquid sold - will be 36mg x 80% = 28.8mg (as the carto holds 1ml, the liquid is 36mg per ml in strength, and we can only use ~80% of it).
This is not the same as what the user is presented with. We need to test the vapor, for that.

A carto (as described above) is equivalent to around 6 cigarettes in terms of the time the liquid lasts combined with the equivalent in nicotine delivery effect (note use of 'effect' as against 'delivered'). That is to say, the average number a group of experienced users will report a carto is equivalent to is about 6 cigarettes, in their estimation. Also, a smoker who smoked 20 a day will average about 4 cartos a day, the cigarette number equivalency of a standard cartomizer thus seeming to be confirmed.

We can also see several other things here:
a. An e-cig carto doesn't seem to have much nic in it compared to a cigarette - from about 150% to 200% of 1 cigarette, depending on the cigarette measured. Note we are comparing like-for-like here: the same terms of reference are being used. We are not mistakenly comparing an e-cig carto's liquid to cigarette smoke, or a cigarette's tobacco to vapor.
b. This nicotine has to be divided between at least 6 'cigarette equivalent' sessions.
c. Perhaps the relative amounts delivered into the smoke and into the vapor differ, which would start to explain the anomaly, as on the surface there does not seem to be enough nicotine in the vapor.
d. Perhaps cigarette nicotine and e-cig nicotine differ in user-availability as well.

Usable materials delivery - vapor
E-cigarette (mainstream) vapor is untested for total content, either by weight/volume, or per session equivalent, but is believed to contain about 1% nicotine (n=1 trial).
(There are no protocols for 'session' measurements as none have been agreed, in contrast to those for tobacco cigarettes. They would need to be different as an e-cigarette is not used in the same way as a tobacco cigarette. It has been demonstrated that if an e-cigarette is used in the same way as a cigarette, zero or very little nicotine is delivered to the end-user).
'1% nicotine' is not the same as what is actually usable by the consumer - for example, nicotine measured in this way, in the form of vapor, might not be able to be metabolysed by the user. We need to test their bloodstream for nicotine, to establish this.

User tests - vapor
A vaper's bloodstream typically shows from 10 to >40 ng/ml of nicotine. This is sufficient for the vaper to be satisfied.
This means they do get nic from vapor, and it is measurable, and it does the job.
At the upper end, the results are about the same as smokers. Many of the e-cig user's tests, though, come in at the lower end of the scale (10-20ng/ml), and the vapers are still satisfied.
Nicotine metabolytes such as cotinine can also be measured in the urine, and there is a relationship between the amount of cotinine measured versus the amount of nicotine consumed and the time elapsed since consumption.
What this tells us is that vapers get nicotine from cigarettes, the effect is measurable in the bloodstream and elsewhere, and it does the job.
Some research suggests the initial speed of nicotine absorption from vapor is much slower than for smoke, and of the order of minutes rather than seconds. Equally, some research shows the results are fast, but not as fast as for smoke - but within 30 seconds.
Users anecdotally report the effect is fast enough, i.e. less than 1 minute, but not as fast as smoke.


Calculating an equivalency
Probably, from this, you can see that getting some sort of direct or measurable equivalent between tobacco cigarettes and e-cigarettes is impossible. It confuses a lot of people including governments. And we didn't even start to discuss these additional issues:

a. Smoke and vapor deliver nicotine in a different way.
b. In cigarette smoke, some nicotine is bound in tar; and in e-cig vapor, some (much? all?) nicotine is bound in the excipient (typically VG or PG). How does this binding affect the delivery?
(We know that there is a major difference between spilling pure nicotine on the skin and spilling PG- or VG-based nic on the skin: there is a time of grace in which the nic can be cleaned off, in the case of PG/VG nic, that is not present with pure nic; and this does not seem related to the strength, showing that the carrier liquid binds the nic in some way.)
c. It has been suggested that since the droplet size in e-cig vapor is around ten times the size of the particulates in cigarette smoke; and that the nic in e-liquid is bound more strongly; and because of these factors the nicotine delivery is less efficient; and also that more nic is absorbed in the buccal and nasal cavities (mouth and nose) than in the lungs. There are no references for this that I could find but these suppositions seem anecdotally supported.
e. Dr Laugesen mentioned that e-cig vapor 'contained about 10% of the nicotine in cigarette smoke' but he did not document this fully, it seems to have been simply a comment in passing, and not necessarily supported by any research. (We would like to see these types of numbers reported as confirmed findings, in the body of a research paper.)


What we know in practice
We know e-cigarettes work because of two things:
a. Millions use them successfully to replace smoking.
b. Vaper's blood tests about the same as smoker's blood for nicotine levels.

We also know that a percentage of e-cigarette users still suffer cravings, but we don't know what percentage, as no research has been done on this. Guesses range from 25% to 75%, so there is no consensus - but we know it is a significant number. These cravings disappear when WTA eliquid or Snus is supplied, seeming to suggest that these persons also need nornicotine / anabasine / anatabine / myosmine, as well as nicotine.

We know that:
a. E-cigarette use is increasing rapidly in all developed countries where they have been introduced. In some countries the growth rate is estimated at 50% to 100% per year (it has slowed down a little, and was higher initially in those countries for which we have 'accurate estimates').
b. E-cigs are more popular than Snus with smokers since the growth in uptake is much higher, where Snus is also available, in new markets where there is no previous experience of either (such as the USA).
c. In the seven years e-cigs have been available, there are no reports of mortality or morbidity worldwide. This fact is interesting for many reasons and deserves further investigation, since in theory nothing new, however innocuous, could be consumed with this result (someone should be reported as harmed or even deceased as a result of its use).
d. In exactly the same timescale, a psychotropic drug for quit-smoking treatment is associated with one multiple murder case, hundreds of suicide deaths, over a thousand suicide attempts, multiple thousands of psychotic events, and a cardiac event rate of one in thirty patients (now reported by two separate clinical trials), indicating that it is responsible for hundreds of thousands of cardiac events (over 62,000 in the US in 2010). A cardiac event may be described as a heart attack although since the mortality rate does not seem high, perhaps the popular description is unjustified.
e. We can therefore clearly see that e-cigarettes are thousands of times safer than Chantix.
d. There are almost certainly cases of nicotine overdose from e-cigarette use due to botched DIY attempts; and cases of intolerance to certain e-liquid ingredients for certain individuals; and even a number of lung issues resulting from e-cig use especially where no proper trials took place to determine the best e-liquid type for that individual.
e. However, on balance, with whatever measures are used, e-cigarette use appears to be extremely safe. The idea that some mechanism could exist that will result in large numbers of users presenting with some form of fatal cancer or similar, after a decade or so, does not seem a viable proposition as neither the agent nor the mechanism are demonstrated. Some new form of disease would be required, which is not currently accepted as likely. In addition, the likelihood that this new disease could produce mortality on the scale of smoking (often quoted as 50% although there does not seem to be solid evidence for this, with only a single clinical trial in the 1950s reporting this) is also not credible. When compared with tobacco smoking, e-cigarette use should prove incomparably safer. One professor of medicine has stated e-cigarettes are likely to be safer than Snus.
f. Nicotine overdose is easily avoided with an e-cigarette: stop vaping when you get dizzy - and reduce the strength of your liquid. It couldn't be much easier. Because the onset of nicotine effect is rapid enough with vaping that consumption can be stopped when symptoms appear, it is hard to go beyond the minor inconvenience stage. The exception to this is if a serious error in DIY is made, and this is a different matter.
g. We could not find any references for successful suicides by swallowing nicotine. Apparently swallowing it induces a vomit reflex, resulting in it being expelled, so in practice it may be difficult to succeed with this method.


Conclusion
We think you will agree that this is a highly-complex subject. The best thing is just to suck it and see: if an e-cig feels about right for you, and it does the job OK - then there is not much need to worry about the technicalities. People already did that, and gave up (see my attempts here), because it is simply impossible to 'convert' e-cigarettes to cigarettes - the only important factor is what the end-user feels about it.

If you really want to play safe - and there is nothing wrong with that - then start with a low-strength nic refill and work up, if you still have cravings.

If you are chain-vaping the strongest possible strength, and you've tried other brands as well (in case one brand is under-marked), and you still have cravings, then you need the other WTAs in tobacco as well as nicotine. Either sit it out until those cravings go, or get some WTA e-liquid or Snus.

Above all don't worry. Enough professors of medicine, doctors, other experts in public health, and above all, expert vapers have confirmed there is no need to worry that it is not necessary for the average person to inquire further.

One area of concern is beginners trying DIY with high-strength nic base. Some will inevitably suffer temporary harm as a result and this cannot be avoided, certainly by bans. However, all current information seems to indicate that this is about as harmful as becoming paralytic drunk by design, as very many people do. Almost all recover from binge-drinking with no apparent ill-effects in the long term, though the social impact of their behavior is another matter...